CLSA-2026-1790704116 libvirt: Fix of 2 CVEs

CVE-2021-3631: Fix insecure sVirt label generation single-category MCS labels in virSecuritySELinuxMCSFind - CVE-2021-3975: Fix use-after-free due to missing monitor lock in qemuProcessHandleMonitorEOF - CVE-2022-0897: Fix missing locking in nwfilterConnectNumOfNWFilters DoS - CVE-2024-1441: Fix...